Analysis of CdTe detectors using I-V characteristics

Cadmium telluride (CdTe) is a compound semiconductor with a wide band gap of 1.44 eV and a cubic zincblende crystal structure. Its high density (5.85 g/cm3) and high atomic numbers (Z(Cd) = 48, Z(Te) = 52) make CdTe an attractive material for X-ray and gamma ray detectors, especially for applications that require high detection efficiency, good energy resolution, and room temperature operation. In this paper, CdTe detectors based on two types of metal-semiconductor- metal structures were studied, with In/Ti Schottky contact from one substrate side and ohmic Pt contact from the opposite side and the second type with both side Pt Ohmic contacts. Current-voltage characteristics in the reverse and forward directions of prepared detectors were measured. The average dark current at bias 70 V was 93 nA for CdTe detectors with Ohmic contact and the dark current at bias 700 V was in interval from 5 to 77 nA for CdTe detectors with Schottky blocking contact.